Nystagmus responses during triangular waveforms of angular velocity about the Y- and Z-axes.

Abstract

Nystagmus slow phase velocity was measured during rotation stimuli consisting of short (12 sec) triangular waveforms of angular velocity. In one test series the horizontal semicircular canals were stimulated and in another test series the vertical canals were stimulated. The data were fit by equations derived from the assumption that the responses depend upon a cupula-endolymph system that responds like an over critically damped torsion pendulum. Mean long time constant (II/δ) values found for the horizontal and vertical canal responses were, respectively, 16 sec and 7 sec, consistent with previous findings, whereas “gain” constants found for the horizontal and vertical canals were, respectively, 8.0 sec and 5.4 sec. Procedures for quickly extracting these parametric values from nystagmus records are described and, for practical reasons, the effects of stimulus distortion on the estimates of parameters were also considered.